Olefins may be polymerized by a variety of transition metal containing catalysts, for example metallocene and Ziegler-Natta type catalysts. More recently, late transition metal containing polymerization catalysts have also been discovered, and among them are nickel and other transition metal containing catalysts in which the metal atom is complexed to a monoanionic and presumed bidentate ligand, see for instance WO9842664, WO9842665, U.S. Pat. No. 6,060,569, U.S. Pat. No. 6,174,975 and S. D. Ittel, et al., Chem. Rev., vol. 100, p. 1169-1203 (2000) (and references cited therein). S. Y. Desjardins, et al., J. Organometal. Chem., vol. 515, p. 233-243 (1996), ibid., vol. 544, p. 163-174 (1997), describe the oligomerization/polymerization of ethylene using nickel complexes of certain pyridine carboxylates.
U.S. Pat. No. 6,174,976 describes the use of certain neutral nickel complexes of ligands containing imino and carboxylate groups to polymerize hydrocarbon monoolefins.
In the following references, Zwitterionic nickel catalysts based on phosphine carboxylate ligands were utilized to carry out ethylene oligomerizations; however, polar monomers were not incorporated in any of the oligomers made with these systems: Komon, Z. J. A., et. al., J. Am. Chem. Soc., 122, 1830-1831 (2000); Komon, Z. J. A., et. al., J. Am. Chem. Soc., 122, 12379-12380 (2000).
Zwitterionic systems have been proposed in U.S. Pat. No. 6,103,658 and U.S. Pat. No. 6,200,925, but no polar monomers were incorporated in any of the polymers made with these systems.
All of the above publications are incorporated by reference herein for all purposes as if fully set forth.
None of these publications describes the complexes disclosed herein. Since polyolefins are important commercial materials, new catalysts for their manufacture are constantly being sought.